This invention relates generally to surgical instruments for use in minimally-invasive surgical procedures such as endoscopy, thoracoscopy, laparoscopy, pelviscopy, and arthroscopy. More specifically, the invention relates to percutaneous visualization systems for use in such minimally-invasive surgical procedures.
In minimally-invasive surgical techniques such as endoscopy, thoracoscopy, laparoscopy, pelviscopy, arthroscopy, and the like, elongated instruments are introduced into the body through small incisions or percutaneous cannulae to perform surgical procedures at an internal site, obviating the need for the large incisions characteristic of conventional, open surgical techniques. Visualization is facilitated by the use of specialized devices known as endoscopes, laparoscopes, pelviscopes, thoracoscopes, or arthroscopes, which typically consist of a rigid, elongated tube containing a lens system and, at the proximal end of the tube, an eyepiece or camera mount. The distal end of the tube is introduced into the body through an incision or cannula, and, by looking through the eyepiece, a surgeon may observe the interior of a body cavity. In addition, a small video camera may be attached to the camera mount and connected to a video monitor to provide a video image of the procedure. Usually, such visualization devices further include a light source at the distal end of the tube for illuminating the interior of the body cavity.
As the complexity of the procedures that can be performed by means of minimally-invasive techniques has increased, so has the demand for higher quality visualization systems to facilitate such procedures. For example, in commonly-assigned co-pending application Ser. No. 08/023,778, filed Feb. 22, 1993, the complete disclosure of which is incorporated herein by reference, new techniques are disclosed for performing coronary artery bypass grafting and other thoracic surgical procedures using minimally-invasive techniques. Coronary artery bypass grafting involves the use of microsurgical techniques to create an anastomosis, usually by suturing, between a coronary artery and either an existing artery such as the mammary artery, or a natural or synthetic arterial shunt connected to an upstream arterial blood source. As described in the forementioned patent application, long-handled microsurgical tools may be introduced through small incisions or cannulae positioned in the intercostal spaces of the rib cage to perform the anastomosis. Such procedures may take a team of surgeons up to several hours to complete. These intricate procedures therefore demand a visualization system that produces an extremely high-quality image of very small surgical sites, and that allows multiple surgeons to simultaneously view a surgical site comfortably over long periods of time.
While many of the visualization devices in current use have proven to be effective for use in certain minimally-invasive surgical procedures, such devices are frequently inadequate for the performance of complex microsurgical procedures such as coronary artery bypass grafting. For example, if just an eyepiece is used on an endoscope, only one person can look through the device at any one time, requiring an individual scope introduced through a separate incision or cannula for each person assisting in or observing the procedure. Further problematic is the difficulty in maintaining the eyepiece in alignment with the surgeon""s eye for continual visualization while manipulating the instruments necessary to perform the procedure. Additionally, because these visualization devices are typically monoscopic, they have poor resolution of depth of field in comparison to a person""s binocular, stereoscopic vision using both eyes.
By mounting a video camera on such visualization devices, more than one person may observe a procedure by watching a video monitor, without the need for additional incisions into the body cavity. However, the miniature video cameras in current use frequently produce sub-optimal image quality in comparison to direct vision through the scope. Further, indirect visualization by means of a video monitor rather than by direct sight is somewhat disorienting, and requires significant training and practice to develop the hand-eye coordination necessary to adeptly perform surgery. Additionally, where multiple surgeons are working in the surgical site under video imaging by a single scope, the video image can be correctly oriented relative to only one of the surgeons at any time. Other surgeons must adjust their actions to compensate for an inverted or otherwise misoriented image. Moreover, because most scopes, video electronics, and video displays in current use are monoscopic, video visualization also fails to provide the depth perception of normal stereoscopic vision.
What is needed, therefore, is a percutaneous visualization system for use in minimally-invasive surgical procedures that facilitates direct, stereoscopic visualization of a body cavity through a small incision or cannula. The visualization system should facilitate hand-eye coordination that is close or equal to that of open surgical procedures. Preferably, the visualization system will have the capability for wide-angle visualization as well as magnification to facilitate the performance of complex microsurgical procedures. Further, the visualization system should allow multiple surgeons to simultaneously view the same surgical site with comfort for long periods of time. The visualization system will preferably be configured for introduction through intercostal spaces of the rib cage for thoracoscopic procedures, but should be useful in any of a variety of minimally-invasive procedures, including laparoscopy, pelviscopy, arthroscopy and the like.
The invention provides a percutaneous visualization system and method that facilitate direct, stereoscopic visualization of a body cavity. The visualization system has both wide angle and magnification capabilities and produces extremely high image quality, thereby facilitating the performance of intricate microsurgical procedures using minimally-invasive techniques. Using the system and method of the invention, multiple surgeons may simultaneously view a surgical site comfortably for extended periods. The visualization system also allows various lenses to be easily interchanged or combined to optimize focal length and field of view. The system may further include a light source to illuminate the body cavity, as well as a passage for introduction of instruments into the body cavity. The system is particularly well-adapted for use in thoracoscopic procedures by positioning in intercostal spaces of the rib cage, but is also useful in endoscopic, laparoscopic, pelviscopic, arthroscopic, and other minimally-invasive procedures.
The visualization system of the invention includes a tubular cannula suitable for percutaneous introduction into a body cavity such as the thorax, abdomen, pelvis, cranium, or joint cavity. The cannula has an optical passage extending from its proximal end to its distal end that is configured to allow stereoscopic visualization of the body cavity. In a preferred embodiment, at least a portion of the optical passage is tapered toward the distal end at a taper angle selected to facilitate stereoscopic visualization of the body cavity through the optical passage. Usually, the taper angle of the optical passage will be at least 5xc2x0 and less than 45xc2x0, and preferably between 5xc2x0 and 20xc2x0.
In one embodiment, the optical passage is open from the proximal end to the distal end to allow surgical instruments, sutures, prostheses, tissue, light or light sources, visualization devices, and the like, to pass through the optical passage into or out of the body cavity. Alternatively, the cannula may include lens means mounted in the optical passage. The lens means preferably comprises a wide-angle lens system, such as a negative focal length lens, and may be permanently fixed or removably mounted in the optical passage. Such a lens means facilitates viewing a field within the body cavity which is substantially larger than the penetration through which the cannula is introducedxe2x80x94that is, substantially larger than the transverse cross-sectional area of the cannula itself. In a preferred embodiment, the lens means is mounted in a sleeve which is configured to be removably positioned in the optical passage. Where the optical passage is tapered, the sleeve is correspondingly tapered so as to nest within the cannula. In this way, the user may look directly through the optical passage in the cannula into the body cavity, or position a sleeve with wide-angle lens in the cannula to widen the field of view. Multiple sleeves with various lenses may be interchanged as the user desires.
The visualization system may further include magnification means that is optically alignable with the optical passage in the cannula. The magnification means preferably comprises a stereo-microscope positionable in alignment with the optical passage proximal to the cannula""s proximal end. In a preferred embodiment, the stereo-microscope has a plurality of binocular eyepieces to allow multiple persons to view the surgical site simultaneously through the optical passage in the cannula. The use of a high-power stereo-microscope produces extremely high image quality at selectable magnification, thereby facilitating visualization of intricate microsurgical procedures. Alternatively, the magnification means may comprise binocular surgical telescopes, or xe2x80x9cloupes,xe2x80x9d worn on the head of the user, much like eyeglasses with magnifying lenses.
The cannula is preferably configured for percutaneous introduction through an intercostal space in the rib cage into the thoracic cavity. The cannula may also be introduced into the abdominal cavity or into the pelvis. To facilitate introduction, the visualization system may further include an obturator or trocar that is positionable in the optical passage in the cannula. The obturator may have a sharpened or rounded tip that extends distally from the distal end of the cannula to penetrate tissue. Once the cannula has been positioned with its distal end in the body cavity, the obturator is removed.
The system may further include means for maintaining the cannula in a particular position or orientation relative to the patient""s body. In a preferred embodiment, the means for maintaining the position of the cannula comprises a support structure that is fixed to the operating table supporting the patient, and a pivotable clamp attached to the support structure which may be clamped to the visualization cannula. In this way, the cannula may be positioned as desired and locked in place with the clamp. Alternatively, the cannula may be secured to the body of the patient, to the surgical drapes, to the surgical microscope, or to other supporting structures.
In a particularly preferred embodiment, the cannula of the invention is coupled directly to the microscope, thereby maintaining alignment between the two and securing the cannula in position. To facilitate interchanging lenses without decoupling the cannula from the microscope, an aperture may be provided in a side of the cannula in communication with the optical passage to allow lenses to be interchanged through the aperture. Alternatively, the sleeve which holds the lens means may be coupled to the microscope, the cannula remaining separate so that it may be positioned in the patient""s body independently of the microscope and the sleeve. A means of coupling is preferably used which allows adjustment of the position of the cannula relative to the microscope along the optical axis of the microscope. This facilitates adjustment of the distance between the microscope objective and the lens means in the cannula to obtain proper focus at a desired distance when used with microscopes having a fixed focal length objective lens. In use, the cannula is usually positioned in the patient""s body before coupling it to the microscope, and proper orientation of the cannula is obtained by direct visualization of the body cavity through the optical passage. With the cannula in position, the microscope is aligned with the cannula and the two are coupled together. Because the cannula enters into the body cavity and may come into direct contact with tissue within the body cavity, it is adapted for easy removal from the microscope for sterilization or disposal after use.
In addition, the visualization system may include means for illuminating the body cavity. The illuminating means may comprise a light source which is independent of the cannula, but, in a preferred embodiment, comprises a plurality of optical fibers fixed to the cannula and extending from its proximal end to its distal end. At the proximal end, the optical fibers may be connected to a light source so as to transmit light into the body cavity.
In a further preferred embodiment, the cannula of the invention includes means for directing a fluid onto a surface of a lens positioned in the passage of the cannula, for purposes such as removing debris or defogging the lens. The fluid directing means may comprise, for example, a lumen extending through the cannula body, a connector at the proximal end in communication with the lumen for connection to a fluid delivery source, and an opening at the distal end in communication with the lumen for directing the fluid onto the surface of the lens. The fluid may comprise a liquid such a saline solution for debris removal and/or irrigation, or a gas such as carbon dioxide for defogging or dehumidifying the lens.
The system and method of the invention offer significant advantages over previous visualization devices for use in minimally-invasive surgery. The invention provides the high image quality, natural hand-eye coordination and correct image orientation of direct vision, while allowing multiple persons to view the surgical site simultaneously. Visualization is further enhanced by the stereoscopic capability of the invention, which greatly improves depth perception. Moreover, the invention allows the use of high-power stereo microscopes with selectable magnification to produce an exceedingly high-quality image, making the invention particularly well-adapted for visualization of microsurgical procedures. Further advantages of the invention include the ability to interchange lenses easily, the capability for wide-angle viewing, as well as the ability to introduce or withdraw surgical instruments, body tissue, or prostheses into or out of the body cavity without the need for additional incisions.
A further understanding of the nature and advantages of the invention may be realized by reference to the remaining portions of the specification and the drawings.